From patchwork Tue Oct 21 10:49:34 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dheeraj Jamwal X-Patchwork-Id: 5117391 Return-Path: X-Original-To: patchwork-ltsi-dev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EB8E4C11AC for ; Tue, 21 Oct 2014 11:33:35 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DC0892010F for ; Tue, 21 Oct 2014 11:33:34 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C2EE820107 for ; Tue, 21 Oct 2014 11:33:33 +0000 (UTC) Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id E117BF19; Tue, 21 Oct 2014 11:05:38 +0000 (UTC) X-Original-To: ltsi-dev@lists.linuxfoundation.org Delivered-To: ltsi-dev@mail.linuxfoundation.org Received: from smtp2.linuxfoundation.org (smtp2.linux-foundation.org [172.17.192.36]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 92DF5F1A for ; Tue, 21 Oct 2014 11:05:35 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by smtp2.linuxfoundation.org (Postfix) with ESMTP id 1D3B01DD15 for ; Tue, 21 Oct 2014 11:05:35 +0000 (UTC) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP; 21 Oct 2014 04:04:34 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,761,1406617200"; d="scan'208";a="617795459" Received: from ubuntu-desktop.png.intel.com ([10.221.122.25]) by fmsmga002.fm.intel.com with ESMTP; 21 Oct 2014 04:04:33 -0700 From: Dheeraj Jamwal To: ltsi-dev@lists.linuxfoundation.org Date: Tue, 21 Oct 2014 18:49:34 +0800 Message-Id: <1413889294-31328-375-git-send-email-dheerajx.s.jamwal@intel.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> References: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org Subject: [LTSI-dev] [PATCH 0374/1094] drm/dp: Add DisplayPort link helpers X-BeenThere: ltsi-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: "A list to discuss patches, development, and other things related to the LTSI project" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ltsi-dev-bounces@lists.linuxfoundation.org Errors-To: ltsi-dev-bounces@lists.linuxfoundation.org X-Virus-Scanned: ClamAV using ClamSMTP From: Thierry Reding Add a helper to probe a DP link (read out the supported DPCD revision, maximum rate, link count and capabilities) as well as power up the DP link and configure it accordingly. Reviewed-by: Alex Deucher Reviewed-by: Jani Nikula Signed-off-by: Thierry Reding --- drivers/gpu/drm/drm_dp_helper.c | 97 +++++++++++++++++++++++++++++++++++++++ include/drm/drm_dp_helper.h | 17 +++++++ 2 files changed, 114 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 84262ed..177ac7b 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -472,3 +472,100 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, DP_LINK_STATUS_SIZE); } EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); + +/** + * drm_dp_link_probe() - probe a DisplayPort link for capabilities + * @aux: DisplayPort AUX channel + * @link: pointer to structure in which to return link capabilities + * + * The structure filled in by this function can usually be passed directly + * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and + * configure the link based on the link's capabilities. + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 values[3]; + int err; + + memset(link, 0, sizeof(*link)); + + err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); + if (err < 0) + return err; + + link->revision = values[0]; + link->rate = drm_dp_bw_code_to_link_rate(values[1]); + link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; + + if (values[2] & DP_ENHANCED_FRAME_CAP) + link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_probe); + +/** + * drm_dp_link_power_up() - power up a DisplayPort link + * @aux: DisplayPort AUX channel + * @link: pointer to a structure containing the link configuration + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 value; + int err; + + /* DP_SET_POWER register is only available on DPCD v1.1 and later */ + if (link->revision < 0x11) + return 0; + + err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); + if (err < 0) + return err; + + value &= ~DP_SET_POWER_MASK; + value |= DP_SET_POWER_D0; + + err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); + if (err < 0) + return err; + + /* + * According to the DP 1.1 specification, a "Sink Device must exit the + * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink + * Control Field" (register 0x600). + */ + usleep_range(1000, 2000); + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_power_up); + +/** + * drm_dp_link_configure() - configure a DisplayPort link + * @aux: DisplayPort AUX channel + * @link: pointer to a structure containing the link configuration + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 values[2]; + int err; + + values[0] = drm_dp_link_rate_to_bw_code(link->rate); + values[1] = link->num_lanes; + + if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) + values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; + + err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); + if (err < 0) + return err; + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_configure); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 8759ce6..17b3a8a 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -301,6 +301,7 @@ #define DP_SET_POWER 0x600 # define DP_SET_POWER_D0 0x1 # define DP_SET_POWER_D3 0x2 +# define DP_SET_POWER_MASK 0x3 #define DP_PSR_ERROR_STATUS 0x2006 /* XXX 1.2? */ # define DP_PSR_LINK_CRC_ERROR (1 << 0) @@ -490,4 +491,20 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux, int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, u8 status[DP_LINK_STATUS_SIZE]); +/* + * DisplayPort link + */ +#define DP_LINK_CAP_ENHANCED_FRAMING (1 << 0) + +struct drm_dp_link { + unsigned char revision; + unsigned int rate; + unsigned int num_lanes; + unsigned long capabilities; +}; + +int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link); + #endif /* _DRM_DP_HELPER_H_ */